1. Field of the Invention
This invention relates to tools and more particularly to a driving tool for use in driving tongue and groove plywood sheets into seated configuration.
2. Prior Art
Tongue and groove mating wood products have been in common use for centuries. Such construction is particularly well-known in flooring and subflooring where the longitudinal side edges of two boards which are to be placed side by side for the flooring or subflooring are respectively tongued and grooved. Tongue and grooving not only provides a relatively secure method of maintaining two adjacent boards together and coplaner, it has the distinct advantage of assisting in reducing bulging.
However, tongue and groove jont connections can be difficult to make, particularly where the tongue is designed to mate snuggly in the groove. This difficulty in seating the tongue in the groove is substantially increased due to the natural tendency of elongated boards to warp. Where slat flooring is used, warp connection and the tongue and groove seating can be accomplished simultaneously with the nailing of the slat to the subfloor. However, where large plywood boards are used either for the subfloor or, as is common in some residential construction, for the entire floor, the width of the plywood sheet or panel increases the difficulty of properly seating the tongue and groove connection.
A standard method of laying such plywood flooring or subflooring involves the use of both bonding glue and nailing. However the glue must be applied to the underside of the plywood or to the supporting joists prior to the seating of the tongue and groove joint. Thereafter it is desirable to properly seat the tongue and groove joint as quickly as possible and to secure the connection by nailing or screwing. Because the plywood board may be quite long, dimensions on the order of 8 feet being common, and because of normal edge warpage, significant increments of force must be used to properly seat the tongue and groove connection.
A common method of seating plywood boards involves the use of a heavy mallet or sledgehammer which is forcibly applied against the free edge of the board. Since significant force is often required, in order to protect the free edge, a protective member is generally placed between the sledge and the plywood edge. In standard practice, 2.times.4 boards are commonly used.
Because it is desired to seat the entire tongue and groove connection substantially simultaneously, the protective 2.times.4 board which is used is generally as long as the plywood board. Thus, where 8 foot plywood sheets are used, an 8 foot 2.times.4 is used as a buffer. Experience has indicated that such boards rarely last beyond the installation of flooring in more than a few rooms. Application of the sledge to the board crushes the wood and dents the board. At the same time the opposite side of the protective board is indented by contact with the edge of the plywood sheet. This practice results in a great waste of otherwise good structural lumber. While this waste could be substantially eliminated by utilizing a noncrushable protective member, such a rigid device would immediately transmit the entire force of the sledge blow directly through to the plywood sheet edge. This would result in localized damage to the plywood sheet edge. This damage is reduced, if not eliminated, when using the 2.times.4 boards due to the resiliency of the wood which both cushions the hammer or sledge blow while at the same time, spreading the force of that blow over a much wider area on the opposite side of the board.
It would therefore be an advance in the art to provide a device for seating tongue and groove plywood sheets to be used between the force applicator (sledgehammer) and the plywood sheet edge which would retain the resilient advantages of wood boards while eliminating the waste presently encountered.